The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent the work is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
A modern wireless device can incorporate functions of a satellite positioning system receiver, of a cellular transceiver, or of a wireless transceiver. When a wireless device functions as a satellite positioning system receiver, the wireless device can specify a device's position by use of only signals from satellites. Satellite based positioning can provide high accuracy, but require a positive line of sight between satellites and the wireless device. Further, receiving and processing satellite positioning signals may consume substantial energy and hence shorten battery duration.
A device can communicate wirelessly with a wireless communication network by employing radio frequency (RF) field propagation. The radio frequency, a frequency within the electromagnetic spectrum associated with radio wave propagation, is supplied to an antenna that creates an electromagnetic field that propagates through space. A component of a wireless communication network can be a wireless station, for example, a cellular base station of a cellular network, or an access point of a wireless local area network (LAN) or a wireless personal area network (PAN). The wireless station can allow a wireless device to communicate with a wired network through an access gateway. Typically, the wireless station broadcasts a beacon signal providing key information necessary for wireless devices to connect to it. A wireless station can serve wireless devices located in a geographic area. When a wireless device functions as a cellular transceiver and/or a wireless transceiver, the wireless device can determine its position using the locations of the wireless stations to which the wireless device can communicate, by triangulating its position based on the strength of the signals received from the wireless stations, if the locations of the wireless stations are known.
As an alternative to triangulation based positioning, database based positioning can be used to determine a position of a wireless device by evaluation of the RF measurements. These measurements are compared to the entries of the database. The corresponding calculations find the best matching database entry and thus lead to a position estimate. Database based positioning can provide high degree of accuracy and is utilized for network-based positioning system. This method does not rely on line of sight conditions but benefits from the more distinct radio patterns of multipath environments. Only network inherent parameters are utilized so that no hardware modifications are required and legacy devices can be employed.